Millions of dead fish surfaced in Maryland’s Chesapeake Bay in the U.S., Tuesday, while similar unexplained mass fish deaths occurred across the world in Brazil and New Zealand. On Wednesday, 50 birds were found dead on a street in Sweden. The news come after recents reports of mysterious massive bird and fish deaths days prior in Arkansas and Louisiana.

The Baltimore Sun reports that an estimated 2 million fish were found dead in the Chesapeake Bay, mostly adult spot with some juvenile croakers in the mix, as well. Maryland Department of the Environment spokesperson Dawn Stoltzfus says “cold-water stress” is believed to be the culprit. She told The Sun that similar large winter fish deaths were documented in 1976 and 1980.

ParanaOnline reports that 100 tons of sardines, croaker and catfish have washed up in Brazilian fishing towns since last Thursday. The cause of the deaths is unknown, with an imbalance in the environment, chemical pollution, or accidental release from a fishing boat all suggested by local officials.

In New Zealand, hundreds of dead snapper fish washed up on Coromandel Peninsula beaches, many found with their eyes missing, The New Zealand Herald reports. A Department of Conservation official allegedly claims the fish were starving due to weather conditions.

While all three events are likely unrelated, they come after recent reports of mysterious dead birds falling from the sky in both Arkansas and Louisiana. Thousands of dead birds were found in Beebe, Arkansas on New Year’s Eve, and a few days later, around 500 of the same species were found 300 miles south in Louisiana. A Kentucky woman also reported finding dozens of dead birds scattered around her home. In the days prior to New Year’s, nearly 100,000 fish surfaced in an Arkansas river 100 miles west of Beebe.